A Virologist Shares Misconceptions About SARS-CoV-2
Rebecca Dutch, PhD, discusses misconceptions about the SARS-CoV-2 virus, how the virus differs from other coronaviruses, and critical information that remains unknown.
Segment description: Rebecca Dutch, PhD, professor of molecular and cellular biochemistry, discusses misconceptions about the SARS-CoV-2 virus, how the virus differs from other coronaviruses, and critical information that remains unknown.
Interview transcript: (modified slightly for readability)
Contagion®: Thanks for joining us today for another Contagion coronavirus update. Today we are joined by Dr. Rebecca Dutch from the University of Kentucky and we're going to be talking a little bit more about the virus. So Dr. Dutch, thanks so much for joining me today. So why don't we start by talking about what makes the SARS-CoV-2 virus different from other coronaviruses that we've seen before?
Dutch: It's what we think is a third in a line of emerging coronaviruses. The first was SARS, which came out in 2002. SARS had slightly a less than 10% mortality rate, but thankfully did not transmit as well as this virus. So that we had a little less than 10,000 cases in the world before it disappeared basically.
The next was MERS or Middle Eastern virus syndrome which came out in 2012. That has continued to have small outbreaks, so we wouldn't say that virus has gone from the world. Unfortunately, it has a very high mortality rate, some getting pretty close to 50%. But, it doesn't appear to transmit well, and we only get sporadic cases here and there.
So this virus has a lot in its genome that's similar to those viruses, you can tell they're very related, but as a few differences. Number one, obviously we're seeing a lot more transmission with this virus, it seems to transmit very rapidly. One of the theories is that this virus may bind its surface receptor, which is something called ACE 2 more efficiently than the original SARS virus did. That might make it better able to do infections, particularly in the upper respiratory tract where the virus would first land. So that may be one of the reasons that it transmits so well. The transmission is probably the biggest thing that we're seeing that is very different. Thankfully, for us the mortality rate while we're still not exactly sure what it is, it's clearly not as high as the original SARS virus or as MERS so more transmission, probably not as lethal as those viruses.
Contagion®: Right. Do we know is there anything else that we know about transmission so far? I know it's a really rapidly emerging situation.
Dutch: What seems to be the case is that it transmits the very best through air. That'd be true for most respiratory viruses. As we're taking precautions, the single most important thing we need to do is to avoid standing near someone that is not in our small group of family or close contact that we're with for any prolonged period of time. Because if they were to have the virus, certainly as a cough, potentially even as they speak, they may be they putting out particles in the air, that could be bringing virus with it. If you're within 6 feet of them, you can breathe those in and that can start an infection. That seems to be the most efficient way to do this. That's where the vast majority is. That's why you'll be so careful about the 6 feet guidance and about social distancing. There is some evidence that this virus is reasonably stable on surfaces. For instance, cardboard up for a few days. Potentially, copper for 4 hours.
It could be door handles other things you could touch, particularly if someone had recently had it all over their hands and touched it, you might pick it up that way. Now, you have to remember those while the virus exists on those surfaces, over time, you're getting fewer and fewer active particles.
Two days after someone touches a door handle, the amount of live virus that's left is way down from what it was initially, but you still need to be careful. That's why we really recommend that you’re constantly washing your hands if you've been out. I mean, if you're in your own home, I only wash my hands normally once I've gotten back in. But, if you're out and about when you come in, the first thing you should do is wash your hands. I always think that I could have touched something.
The other thing is when you're out, do not touch your face. It's not going to come into your hand, so you don't want to take your hand and touch your face and give it to yourself that way. Those seem to be the things we know about the mode of transmission.
The other thing that seems surprising with this virus, and is one of the reasons it's been hard to get a handle on is it appears that people 2 groups of people can spread it. We generally don't think that, we think of people who are already showing symptoms and spreading. But it looks like even people who will get symptoms may have a pretty active infection for a little while before they get those symptoms. There are real questions as to whether they're active spreaders.
But it looks like even people who will get symptoms may have a pretty active infection for a little while before they get those symptoms. And there's real question as to whether they're active spreaders. There was a new paper in Nature that suggested they could culture live virus out of people in the days before symptoms ever showed up. You could do a swab and there is live virus there. So that's quite possible that you could be spreading it before you know. That's even true with flu, about a day or so before you get sick, you're spreading pretty well, this may be longer. The other thing is there seems to be a subset of the population who really doesn't get any symptoms. They don't know they've had the virus. But most of the studies that are being done with that now suggest that they actually can spread. Even though you don't think you're sick, or the person you're talking to doesn't look sick that doesn't mean they don't have the virus. So you still have to take the same progressions.
Contagion®: At this time, do we know anything about the risk of virus mutation when it comes to SARS-CoV-2?
Dutch: There are 2 things to talk about when we talk about mutation. They're important to understand and it's important for the public to understand so they don't get scared when they hear things. SARS-Cov-2 is what's called an RNA virus. What that means is that the genetic material, the stuff that makes it is made up of something called RNA, which is a different thing than our genetic material which is made up of DNA. RNA viruses do a special process where they copy RNA to RNA. And when they do that, they always make mistakes. Now the coronaviruses have fixed some of their mistakes, they're actually the least mistake prone RNA viruses. But they still make way more mistakes than we do. So in a normal replication, this virus is going to make lots of copies of itself that have little errors in them. That type of mutation is normal. So if you were to look at all the viruses being made, you're seeing little changes here and there. What you look at instead is what's the average? If I looked at all the particles I pull out, what's the average sequence I see? Is that changing? There the news is really good. That sequence is not really changing, it looks very constant. So there's no good evidence that we're seeing any kind of major shift in this virus. That's very good news for creation of vaccines and other things like that. I should also point out that we all worry about mutation in the sense of whether something will be more deadly. But it's also possible where viruses slowly evolve. The virus that's being transmitted is the one that transmits best to select for the little changes that make them move best person to person. It's very common for those changes to make the virus less dangerous. Right now, we're seeing no major changes. But at this point, scientists aren't particularly worried about the changes, because if we see them, there's a good chance any changes would actually make it less dangerous, not more.
Contagion®: Right. So my next question is actually submitted from a member of our audience. And that person wants to know, is there evidence of a carrier status in people who have recovered from COVID-19 that could continue spreading the infection?
Dutch: I will say right off that we do not know for sure the answer to this. In general, with viral infections, if someone is fully recovered, they don't tend to spread something very well. That same Nature paper I refer to did look at people after they'd been released from the hospital, after they're asymptomatic. They could find traces of viral RNA for several weeks afterwards, which would suggest there's still some viral replication going on. But that doesn't tell us they can spread, because it's possible. There's a little bit of replication, but not enough to have all the replication you need to make lots of particles you could cough out. I would say it's not impossible, but that wouldn't be your major worry. They seem to be resolving pretty quickly. And within a few weeks, it looked like that number went down to pretty much zero.
Contagion®: Right. So and my next question for you is, what are some of the most common misconceptions about the virus that you've heard?
Dutch: I think one of the first ones that was a major misconception is the idea that this was somehow manmade. That somehow nature could not have done this. Realistically, as a virologist, we're all aware that nature can create all sorts of things and that there's an awful a lot out there. There were studies more than 5 years ago from some outstanding coronavirus labs that showed that there were coronaviruses in bats that look very close to what we're dealing with now. They even mentioned that there were only a small number of changes that would likely have to happen for this to be something that could replicate in humans. So this kind of shift about a virus that was in an animal system coming into humans is something we see.
There's nothing surprising about the starting other than the fact that none of us feel prepared in the end. I teach a virology class and we do talk about emerging diseases and the reality that pandemics may well happen. I think that's one of the major misconceptions; this idea that somehow, we had to create this, nature wouldn't. I think another misconception potentially is that this has never happened before. We've been really fortunate a lot because of outstanding medical care and the advances of science than infectious diseases have not been as major an impact on most of the first world as it used to be. If you'd started back 100 years ago and gone back beyond that infectious diseases were, these kinds of events were normal and people just accepted them. We are fortunate that we're doing so well. So I hear almost a misconception that science isn't curing this yet. I look and say, we are making amazing progress, considering how short a time this virus has been in the human population.
Contagion®: So my last question for you, Dr. Dutch is from a virologist's perspective, what are the biggest questions that you have that remain unanswered right now?
Dutch: I think there will be tons of questions about how this virus might differ in terms of each of the details of its lifecycle that we'll need to tease out once we have more time and resources to do those. Right now, for me, the biggest questions are, what percent of the population actually gets this virus and doesn't have significant symptoms? We do not know that yet. And until we do, it's really difficult to have a good picture of what's actually happening in this epidemic. Once we know the number, the next thing will be to try to start teasing out why. What is it about some people versus others that they get this much worse? Are there people who have risk factors or genetic backgrounds that make them more prone to severe disease? Are they just unlucky and they got a lot of virus? You know, they took in billions of particles and someone else took in 1000.
We don't know those answers, but those are going to be really crucial, not just for understanding SARS-CoV-2, but for understanding any future pandemics. I think those will be a big start. I also think long term I'd really like to see us better understand both coronaviruses and other types of RNA viruses, all the details of the replication that would help a lot with developing very rapid antivirals. There's lots of bits of how the virus actually functions that we're going to need to tease apart. First, so we can protect against this one. Second, so we can better predict the next time.
Contagion®: Great, Dr. Dutch. Thanks so much for joining me today. We really appreciate it.
Dutch: You're welcome. Thank you.